With so many critical plot points omitted from the cinematic version of “Harry Potter and the Half-Blood Prince,” I’m relieved the last book in the series will be made into two movies. The adventure and mischief we expect from Harry (Daniel Radcliffe) and best friends Ron Weasley and Hermione Granger are lacking this time around. But the sixth installment in the Harry Potter film franchise is still a force to be reckoned with, brimming with infectious humor, temperamental teen romance and the tale of two boys on very separate paths. And Radcliffe, the linchpin upon whose shoulders this eight-part series rests, has grown as an actor, demonstrating his comic chops to hysterical effect in the Liquid Luck sequence.

The grown-up Voldemort (Ralph Fiennes) doesn’t appear in “Half-Blood Prince,” but his sinister presence is felt throughout most of the 2 ½ hours, from the dark, narrow, sinuous corridors in Diagon Alley and even Hogwarts to the overall air of menace hanging over the world; even the muggles have noticed the difference in the atmosphere. The two actors who portray the Dark Lord in his youth—Hero Fiennes-Tiffin and Frank Dillane—are aptly cast, both in appearance and demeanor. Fiennes-Tiffin, the adult Fiennes’ nephew, is downright chilling when he tells Dumbledore he can make people hurt. In retrospect, as we watch Dumbledore reveal memories of Tom Riddle to Harry through his Pensieve, we wonder why no one saw early on the warning signs of his moral corruption and hunger for power at all costs.

The movie begins with death and destruction being meted out by three Death Eaters who hurtle from place to place in swirling jets of black smoke. The scenes involving them are dark and monochromatic, like much of director David Yates’ grim vision for the movie. Against this ominous landscape—sunlight is scarce in this production—“Half-Blood Prince” focuses, for the first time, on the personal lives of its adolescent main characters to such a degree you start to wonder if all the adults have been stuffed into a Vanishing Cabinet. We don’t even get the chance to mock and laugh at the predictable absurdity of the Dursleys, as they are entirely absent from this movie.

The agonies and the ecstasies of young love become a central plot, with the added peril of magic. It’s Hermione’s turn to feel the sting of jealousy (remember in “Goblet of Fire,” when she attracted the attentions of a certain world-renowned Quidditch player, much to Ron’s irritation?). After a Quidditch victory—what is it about these Hogwarts girls and their susceptibility to airborne athletes?—Ron’s public snogging session with Lavender Brown causes a devastated Hermione to rush out of the Gryffindor common room. Emma Watson shows she can handle the dramatic moments just as well as she can the more comedic ones. In another scene, Rupert Grint elicits a lot of laughter when Ron accidentally consumes a powerful love potion and waxes poetic about the beauty of the moon and a girl he’s never even met. Meanwhile, a sweet romance grows slowly and quietly between Harry and Ron’s younger sister, Ginny (Bonnie Wright), who looks a great deal like Lily Potter must have in her teen years.

“Half-Blood Prince” does not concentrate solely on the affairs of the heart, though. The movie also illustrates the extraordinary growth that teens must go through and the hard decisions they are forced to make—often at too young of an age—in the storyline of Harry’s longtime nemesis, Draco Malfoy (Tom Felton). Unlike Harry, Draco has grown up in the lap of luxury, with the love and adoration of both his parents. He’s a spoiled brat who has gotten away with abusing and bullying other kids because his parents have always protected him from harm—until now.

With his dad in Azkaban (for you Muggles unfamiliar with HP, that’s a wizard prison) and his family in disgrace, no one can protect Draco from Voldemort. He’s in a precarious position, with a horrifying deed to perform at which he has little chance of succeeding. Instead of being surrounded by his entourage—you almost miss the slavish and superbly stupid Crabbe and Goyle—we catch glimpses of him alone, always nattily dressed in a slim-fitting black suit while wandering the school hallways or lurking in the Room of Requirement. For perhaps the first time in the history of Harry Potter, Draco deserves our sympathy. You realize how being a chosen one has alienated him from everyone else, even his closest friends, whereas Harry’s destiny has only drawn Ron and Hermione closer to him.

To emphasize the sharp divide between him and the rest of his classmates, a clever shot shows Ron and Lavender snogging on a staircase, only to pan to Felton standing on a balcony, staring off into the night, looking lost and forlorn. The scenes where Draco’s crying spills into the night have nothing to do with unrequited love or a failed romance but they are heartrending nonetheless. Felton, who in the past has overacted and literally spit out his lines, particularly the insults he snarls at Harry, demonstrates restraint in his performance and is far more effective as a tortured, brooding Draco. He doesn’t speak much either, but his lean, pale face says enough. He’s one of the few people who looks pensive after Dumbledore’s first-day speech about a former student at the school who made all the wrong choices.

The time spent on the budding teen romances and Draco’s development as a character in great turmoil comes at the expense of other developments. With the exception of a lesson by Professor Horace Slughorn (the wonderful Jim Broadbent)—really, can any school year at Hogwarts commence without the addition of a new teacher?—“Half-Blood Prince” doesn’t spend any time in the classroom. We see Professors McGonnall (Maggie Smith, in an unfortunate wardrobe consisting of lots of pointy details) and Snape (the delightfully acerbic Alan Rickman) roaming the school grounds, but neither of them do any actual teaching onscreen. That Rickman, who can inject more sarcasm into one syllable than most people can hope to fit in a sentence, doesn’t have much screen time in “Half-Blood Prince,” is a waste of formidable talent. He’s one of the most enjoyable aspects of Hogwarts, in spite of his venom often being directed at Harry.

Dumbledore fans will rejoice at the elevated interaction between Harry and the headmaster of Hogwarts School of Wizardry and Witchcraft. A more somber, businesslike Dumbledore (Michael Gambon) is preparing Harry for his eventual confrontation with Voldemort, trying to arm him with knowledge about the Dark Lord’s weaknesses and past. His plan includes Harry retrieving a memory from Slughorn about a conversation he once had with a sixth-year Tom Riddle. I’ve always lamented the loss of the late Richard Harris as Dumbledore, and “Half-Blood Prince” makes his absence more painfully obvious. Although Gambon is a fine actor, he doesn’t capture Dumbledore’s essence. Gambon’s too authoritative, too energetic, too fierce; the Dumbledore from the books and Harris’ performances in the first two movies is more refined and quietly commanding.

Jessie Cave is hilarious as the obsessively possessive Lavender. As the well-built but annoyingly arrogant Cormac McLaggen—Ron’s rival at the Quidditch tryouts—Freddie Stroma provides comic relief whenever he leers at the mortified Hermione. Evanna Lynch, as the loony and lovable Luna Lovegood, is always a bewitching distraction. Helena Bonham Carter has a raucous time as the crazed Bellatrix Lestrange, cackling as she wreaks havoc within and without Hogwarts’ walls. Dave Legeno doesn’t have any lines as Fenrir Greyback, but he manages to convey malevolence with a single glance.

There are pivotal scenes in the book missing from the movie: The Quidditch match won by Ginny playing Seeker and the spontaneous kiss she shares with Harry later in the common room; Dumbledore more fully explaining his theory about Voldemort’s Horcruxes to Harry; the engagement between Bill Weasley and Fleur Delacour—and Mrs. Weasley’s initial opposition to it. Little attention is even paid to the object inspiring the title: The old, worn textbook with handwritten notes and corrections scribbled all over its pages, turning Harry into a Potions wunderkind and making him one of Slughorn’s favorites. There are some pointless scenes in the movie that don’t exist in the book: Harry reading a paper at a coffeehouse where he meets and flirts with a pretty waitress; the fight at the Burrow that ends with Bellatrix setting the house on fire. The ending is perhaps the weakest part of the movie, lacking the battle scene at the school (one can’t help but think the students needed the practice of more dueling, given what’s to come in “Harry Potter and the Deathly Hallows”).

“Half-Blood Prince” lacks the smooth pacing of “Order of the Phoenix” and the narrative flair of “Prisoner of Azkaban,” even though quite a few of the scenes are wondrous to behold (the London bridge twisting and falling, the lake within a seaside cave). More emotionally charged and visually enthralling than usual, “Half-Blood Prince” does an admirable job of whetting our appetite for parts one and two of “Harry Potter and the Deathly Hallows.” Those of us who are avid Harry Potter fans will rush to see them even if a Death Eater is standing in our way.